Billet piercing and extrusion



0d. 8, 1968 A, MURPHY ETAL 3,404,552

BILLET PIERCING AND EXTRUSTON Filed May 17, 1965 m m w w nu, rrrrn INVENTOR CARL M. FILAK ALFRED MMURPHY 45%, PM W fi'gg United States Patent ABSTRACT OF THE DISCLOSURE An extrusion press extrudes metal tubing by a twostroke cycle. In the first forward stroke a ram without a mandrel crushes and upsets the billet. The ram is withdrawn and, with a piercing mandrel afiixed, pierces and extrudes the upset billet in a second forward stroke. To provide centering, the front of the mandrel base is tapered to mate with an internal cavity in the ram.

This invention relates to piercing metal billets and extruding them into metal tubing.

It is known in the prior art that in providing annular billets for the extrusion of metal tubing, the annular billet may be cast directly, or a solid billet may be bored or pierced prior to being located within the extrusion press.

It is also known in the prior art that in the extrusion of metal tubing the billet may be located within the container, and pierced immediately prior to being extruded. Performing this piercing with the extrusion press is not only economical, but also prevents the inner surface of the billet from accumulating foreign material during storage and becoming exposed to air and thereby oxidized, increasing mandrel wear and possibly leading to defects in the tubing.

Conventionally the pircing is performed on a piercing extrusion press wherein a piercing mandrel is independly movable with respect to the ram. After the main ram crushes the billet, it is stopped and the piercing mandrel is driven through the billet and into the die orifice. Then the ram is advanced to extrude the metal over the stationary mandrel and through the die orifice.

Although such conventional piercing presses are relatively efficient, they are also quite complicated and expensive. Accordingly the present invention is directed to adapting conventional non-piercing extrusion presses for piercing billets and immediately thereafter extruding them into metal tubing. This is achieved by alfixing a piercer to the ram and providing means to keep it centered during piercing and extrusion.

For a better understanding of the invention, and of its other details, objects, and advantages, reference is now made to the accompanying drawings which show, for purposes of illustration only, present preferred embodiments of the invention.

In the drawings, FIGURES 1 and 3-5 are semi-diagrammatic sectional elevation views showing a sequence of operations in accordance with the invention, while FIGURE 2 is a plan view of a portion of the apparatus used in carrying out the invention.

Referring now to the drawings, the extrusion press comprises ram 10 having a detachable head portion 12 with centering land 13, container 14 having at its front end a tapered sealing surrface 16, and die means 18, which may include a die holder. Die means 18 has an extrusion orifice 20 and rear tapered sealing surface 22 adapted to mate with surface 16 of container 14 so as to form a metal-tight seal and to center container 14 with respect to die means 18. Attached to the front end of ram 10 is relatively short centering projection 24 having an enlarged base which includes a tapered portion 26 and a larger, cylindrical portion 28. Centering projection 24 fits into the top of ram 10 with cylindrical lug portion 28 mating with slot 30 in ram 10 and tapered portion 26 mating with corresponding passageway surfaces 32 in ram 10. Used with ram 10 is guide dummy block 34 having at one end a passage 35 which is enlarged and tapered for mating with the base of centering projection 24.

Initially guide dummy block 34 and metal billet 36 are loaded into container 14, container 14 being abutted against die means 18 either before or after such loading, thereby forming a metal-tight seal between surfaces 16 and 22; see FIGURE 1. Ram 10 then advances so that centering projection 24 mates with guide dummy block passage 35, centering guide dummy block 34, and billet 36 is crushed and upset against the face of die means 18 and the inner wall of container 14; see FIGURE 3. Ram 10 is then retracted from the rear of container 14, and centering projection 24 replaced by piercing mandrel 38 having an enlarged, tapered base which is identical to that of centering projection 24 and fits into ram 10 in the same manner. Guide dummy block 34 remains adhered to billet 36 and thereby centered; see FIGURE 4. Ram 10 is then advanced back into container 14 so that piercing mandrel 38 pierces billet 36. During piercing, passage 35 in guide dummy block 34 keeps piercing mandrel 38 accurately centered. When the front face of ram 10 reaches guide dummy block 34, the tip of piercing mandrel 38 is disposed within orifice 20 of die means 18 and extruding of the tube 40 begins. During extruding, the pressure of the metal flowing through die orifice 20 and around piercing mandrel 38 serves further to center piercing mandrel 38; see FIGURE 5.

The slot arrangement whereby centering projection 24 and piercing mandrel 38 fit into ram 10 not only facilitates rapid interchange of centering projection 24 and piercing mandrel 38, but also provides piercing mandrel 38 with a slight amount of play with respect to ram 10. This play enables piercing mandrel 38 to float, and thereby accurately to respond during piercing and extruding to the several centering influences mentioned above.

While present preferred embodiments of the invention have been illustrated and described, it will be understood that the invention may be otherwise variously embodied and practiced within the scope of the claims set forth below. It will be understood further that certain of the steps recited in these claims may be performed in any convenient order.

What is claimed is:

1. A method of extruding a solid metal billet to form metal tubing by means of apparatus including a die means having therein an extrusion orifice, a container disposed rearwardly of and aligned with said die means, a ram aligned with said die means and said container and mounted for movement into said container, a centering projection having an enlarged tapered base and adapted to be affixed to the front end of said ram with said enlarged tapered base thereof abutting said ram, a piercing mandrel likewise having an enlarged tapered base and likewise adapted to be aflixed to the front end of said ram with said enlarged tapered base thereof abutting said ram, and a guide dummy block having therein an axial passage which has a tapered portion at one end for mating with said enlarged tapered base of either said centering projection or said piercing mandrel when either said centering projection or said piercing mandrel is inserted therethrough, said method comprising the steps of:

(A) abutting said container against said die means so as to form therewith a metal-tight seal;

(B) afiixing said centering projection. to said front end of said ram with said enlarged tapered base thereof abutting said ram;

(C) disposing said billet in said container;

(D) disposing said guide dummy block in said container rearwardly of said billet;

(E) advancing said ram into the rear of said container, so that said centering projection extends through said passage in said guide dummy block and said enlarged tapered base of said centering projection mates with said enlarged tapered portion of said passage in said guide dummy block, thereby centering said guide dummy block with respect to said ram, said container, and said orifice in said die means;

' (F) continuing to advance said ram until said billet is completely crushed and upset against said die means and said container;

(G) retracting said ram from the rear of said container, said guide dummy block remaining adhered to said billet and thereby centered with respect to said ram, said container, and said orifice in said die means;

(H) removing said centering projection from said front end of said ram;

(I) affixing said piercing mandrel to said front end of said ram with said enlarged tapered base thereof abutting said ram;

(J) advancing said ram into the rear of said container, so that said piercing mandrel, extending through and being centered by said passage in said guide dummy block, pierces a cylindrical cavity along the axis of said upset billet; and

(K) continuing to advance said ram, thereby extruding said billet through said orifice in said die to form said extruded tubing, said enlarged tapered base of said piercing mandrel mating with said enlarged tapered portion of said passage in said guide dummy block, and the metal forming said tubing flowing uniformly around said piercing mandrel through said orifice in said die means, thereby main taining said piercing mandrel in alignment with said ram, said container, and said orifice in said die means.

2. The method according to claim 1 wherein said piercing mandrel is affixed to said ram in such a manner as to be slightly movable with respect thereto and thereby is easily centered during said piercing and said extruding.

3. In an extrusion press for extruding a solid metal billet to form metal tubing, the combination comprising:

(A) a die means having an extrusion orifice; (B) a container disposed rearwardly of and aligned with said die means;

(C) a piercing mandrel having, from front to rear,

(1) a piercing nose, (2) a relatively long, cylindrical male extruding surface, and (3) an enlarged base including (a) a tapered portion and (b) a lug portion disposed rearwardly of said tapered portion; and (D) a ram aligned with said container and mounted for movement into and through said container, said ram having at its front end (1) a slot (a) extending radially through said ram, (b) spaced from the front surface of said ram, and (c) having a width slightly greater than the width of said lug portion of said enlarged base of said piercing mandrel, and v (2) a passageway communicating at its rear end with said slot and at its front end with said front surface; (B) so that when said piercing mandrel is afiixed to said ram with said lug portion of said piercing mandrel disposed within said slot in said ram with said piercing nose, said male extruding surface, and at least a part of said tapered portion of said enlarged 4 base of said piercing mandrel protruding forwardly of said front surface of said ram, said piercing mandrel is responsive to centering influences acting upon its said piercing nose, its said cylindrical male extruding surface, and its said protruding tapered por tion of its said enlarged base.

4. In an extrusion press for extruding a solid metal billet to form metal tubing, the combination according to claim 3 comprising further a guide dummy block having therein an axial passage which has a tapered portion at one end, said axial passage being dimensioned so as to fit closely with said piercing mandrel when said piercing mandrel is inserted therethrough with said protruding tapered portion of said enlarged base of said piercing mandrel closely mating with said tapered portion of said axial passage.

5. A method of extruding a solid metal billet to form metal tubing by means of apparatus including a die means having therein an extrusion orifice, a container disposed rearwardly of and aligned with said die means, a ram aligned with said die means and said container and mounted for movement into said container, a centering projection adapted to be afiixed to the front end of said ram, a piercing mandrel likewise adapted to be aifixed to the front end of said ram, and a guide dummy block having therein an axial passage for receiving either said centering projection or said piercing mandrel, said method comprising the steps of:

(A) abutting said container against said die means so as to form therewith a metal-tight seal;

(B) affixing said centering projection to said front end of said ram;

(C) disposing said billet in said container;

(D) disposing said guide dummy block in said container rearwardly of said billet;

(E) advancng said ram into the rear of said container, so that said centering projection extends through said passage in said guide dummy block, thereby centering said guide dummy block with respect to said ram, said container, and said orifice in said die means;

(F) continuing to advance said ram until said billet is completely crushed and upset against said die means and said container;

(G) retracting said ram from the rear of said container, said guide dummy block remaining adhered to said billet and thereby centered with respect to said ram, said container, and said orifice in said die means;

(H) removing said centering projection from said front end of said ram;

(I) afiixing said piercing mandrel to said front end of said ram;

(J) advancing said ram into the rear of said container, so that said piercing mandrel, extending through and being centered by said passage in said guide dummy block, pierces a cylindrical cavity along the axis of said upset billet; and

(K) continuing to advance said ram, thereby extruding said billet through said orifice in said die to form said extruded tubing, said piercing mandrel mating with said passage in said guide dummy block, and the metal forming said tubing flowing uniformly around said piercing mandrel through said orifice in said die means, thereby maintaining said piercing mandrel in alignment with same ram, said container, and said orifice insaid die means.

6. The method according to claim 5 wherein said piercing mandrel is affixed to said ram in such a manner as to be slightly movable with respect thereto and thereby is easily centered during said piercing and said extruding.

7. In an extrusion press for extruding a metal billet to form metal tubing, the combination comprising:

(A) a. mandrel having, from front to rear,

(1) a relatively long, cylindrical male extruding surface, and

(2) an enlarged base having a tapered portion whose cross-section increases with distance from said male extruding surface; and

(B) a ram having at its front end a cavity (1) extending radially through said ram, and

(2) defined at least partly by a tapered internal surface adapted to mate with said tapered portion of said enlarged base of said mandrel.

8. A two-stroke method of extruding a solid metal billet to form metal tubing by means of apparatus including a die means having therein an extrusion orifice, a container disposed rearwardly of and aligned with said die means, a ram aligned with said die means and said container and mounted for movement into said container, and a piercing mandrel adapted to be affixed to the front end of said ram, said method comprising the steps of:

(A) preparing for extruding by providing that said container is abutted against said die means so as to form a metal-tight seal and that said billet is disposed in said container;

(B) advancing said ram, without a mandrel attached to it, into the rear of said container until said billet is crushed and upset against said die means and said container;

(C) retracting said ram from the rear of said container;

(D) affixing a piercing mandrel to the front end of said ram;

(E) advancing said ram into the rear of said container, so that said piercing mandrel pierces a cylindrical cavity through said upset billet; and

(F) continuing to advance said ram, thereby extruding said billet through said orifice in said die to form said tubing.

9. A two-stroke method of extruding a solid metal billet to form metal tubing by means of apparatus including a die means having therein an extrusion orifice, a container disposed rearwardly of and aligned with said die means, a ram aligned with said die means and said container and mounted for movement into said container, a piercing mandrel adapted to be aflixed to the front end of said ram, and a dummy block having therein an axial passage, said method comprising the steps of (A) preparing for extruding by providing that said container is abutted against said die means so as to form a metal-tight seal, that said billet is disposed in said container, and that said dummy block is disposed in said container behind said billet;

(B) advancing said ram, without a mandrel attached to it, into the rear of said container until said billet is crushed and upset against said die means and said container;

(C) retracting said ram from the rear of said container said dummy block remaining adhered to said billet;

(D) affixing a piercing mandrel to the front end of said rarn;

(E) advancing said ram into the rear of said container, so that said piercing mandrel passes through said axial passage in said dummy block and pierces a cylindrical cavity through said upset billet; and

(F) continuing to advance said ram, thereby extruding said billet through said orifice in said die to form said tubing.

References Cited UNITED STATES PATENTS 976,529 11/1910 Westerman. 2,337,804 12/1943 Dempsey. 3,054,177 9/ 1962 Duhamel. 1,859,990 5/1932 Scheenstedt 72-264 2,713,418 7/1955 Kent 72-273 FOREIGN PATENTS 258,083 9/ 1926 Great Britain.

CHARLES W. LANHAM, Primary Examiner. K. C. DECKER, Assistant Examiner. 

